The origin of the fast modulation characteristics of deep ultraviolet (DUV) AlGaN light-emitting diodes (LEDs) grown on AlN/sapphire templates with vicinal off-angles is reported by employing time-resolved electroluminescence (EL) and micro-imaging experiments. The LEDs have recently demonstrated Gbps-class optical wireless communication (OWC) under both room-lighting and direct-sun. The frequency response (f3dB) of the LED reached 184 MHz, which is far beyond expectations by considering the size of the LEDs. Since self-organized micro-LED structures with a low electric capacitance (C) are observed by the EL experiments, the compatibility of high efficiency and fast modulation nature of the AlGaN LEDs is explained. Our approach can overcome the dilemma, where micro-LEDs can be modulated fast but have low power, and therefore, the self-organized micro-LED structure is an ideal solution to realize practical DUV OWCs.
Self-organized micro-light-emitting diode structure for high-speed solar-blind optical wireless communications
K. Kojima, Y. Yoshida, M. Shiraiwa, Y. Awaji, A. Kanno, N. Yamamoto, A. Hirano, Y. Nagasawa, M. Ippommatsu, S. F. Chichibu; Self-organized micro-light-emitting diode structure for high-speed solar-blind optical wireless communications. Appl. Phys. Lett. 20 July 2020; 117 (3): 031103. https://doi.org/10.1063/5.0013112
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